Abstract
Precision farming is important to development agricultural production systems and has created a need for spatial data on crop yield and soil characteristics. The objectives of this research were to identify: (i) the spatial and structural variation of soil properties across the landscape; (ii) how yields are related to these soil properties; and (iii) how information of spatial variability within soil physical, chemical, and biological properties can be used to asses in field soil degradation. On farm research was conducted on center-pivot-irrigated fields in Adams and Buffalo Counties, Nebraska, during 1997 and 1998. Samples were taken and analyzed soil physical, chemical, and biological properties, plant population, leaf tissue analysis for nutrients, and grain yields. Factor analysis, multivariate linear regressions, and geostatistics were used to explore soil and crop variability, and classify and map soil properties in the fields. On the farm field with a finer textured silty clay loam soil, soil variation was decomposed into five factors, which accounted for 75% of the total variance. Regression models based on these showed that soil fertility as related to available phosphorus and manganese, as associated with organic matter, was associated with 73% of corn yield variability. However, the application of Mn and P fertilizers did not improve significantly the corn grain yield. These indicated that yields were limited by constraints other than P and Mn. The results suggest the need ofr careful interpretation when using statistical models to seek cause and effect relationships related to yield variability in fields. On the farm field characterized by sandy soils, most of the soil variation related to crop growth was described by five factors, which collectively explained 85% of the total soil variability. Regression models based on these factors were associated with 50% of the corn yield variation. Soil physical-chemical factor, as related to organic matter, texture, bulk density, and pH had the largest effect on the variation of corn yield. Loss of organic matter due to erosion, intensive tillage and input of nitrogen fertilizer, acidification and compaction were some indicators of soil and environmental degradation under current management practices.
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Claims 8
Claim · model-written summary
Soil fertility related to available phosphorus and manganese, associated with organic matter, was associated with 73% of corn yield variability.
- Taxon
- corn
Zea mays subsp. mayse2 - Compound
- available phosphorus and manganesee1
- Outcome
- corn yield variabilitye1
- Value
- 73%e1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“soil fertility as related to available phosphorus and manganese, as associated with organic matter, was associated with 73% of corn yield variability”
e2“the application of Mn and P fertilizers did not improve significantly the corn grain yield”
Claim · model-written summary
Application of Mn and P fertilizers did not significantly improve corn grain yield.
- Taxon
- cornZea mays subsp. mayse2
- Treatment
- application of Mn and P fertilizerse2
- Outcome
- corn grain yielde2
- Direction
- did not improvee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“the application of Mn and P fertilizers did not improve significantly the corn grain yield”
Claim · model-written summary
Corn yields were limited by constraints other than P and Mn.
- Taxon
- cornZea mays subsp. mayse2
- Outcome
- yieldse3
- Qualifier
- constraints other than P and Mne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“These indicated that yields were limited by constraints other than P and Mn”
e2“the application of Mn and P fertilizers did not improve significantly the corn grain yield”
Claim · model-written summary
On sandy soils, five factors explained 85% of the total soil variability.
- Taxon
- cornZea mays subsp. mayse5
- Outcome
- total soil variabilitye4
- Value
- 85%e4
- Setting
- sandy soilse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“On the farm field characterized by sandy soils, most of the soil variation related to crop growth was described by five factors, which collectively explained 85% of the total soil variability”
e5“Regression models based on these factors were associated with 50% of the corn yield variation”
Claim · model-written summary
Regression models based on the sandy-soil factors were associated with 50% of corn yield variation.
- Taxon
- cornZea mays subsp. mayse5
- Outcome
- corn yield variatione5
- Value
- 50%e5
- Setting
- sandy soilse4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Regression models based on these factors were associated with 50% of the corn yield variation”
e4“On the farm field characterized by sandy soils, most of the soil variation related to crop growth was described by five factors”
Claim · model-written summary
Soil physical-chemical factors related to organic matter, texture, bulk density and pH had the largest effect on corn yield variation on sandy soils.
- Taxon
- cornZea mays subsp. mayse6
- Compound
- organic mattere6
- Outcome
- variation of corn yielde6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Soil physical-chemical factor, as related to organic matter, texture, bulk density, and pH had the largest effect on the variation of corn yield”
Claim · model-written summary
Loss of organic matter, intensive tillage, nitrogen input, acidification and compaction were indicators of soil and environmental degradation under current management practices.
- Taxon
- cornZea mays subsp. mayse2
- Outcome
- soil and environmental degradatione7
- Qualifier
- Loss of organic matter due to erosion, intensive tillage and input of nitrogen fertilizer, acidification and compactione7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Loss of organic matter due to erosion, intensive tillage and input of nitrogen fertilizer, acidification and compaction were some indicators of soil and environmental degradation under current management practices”
e2“the application of Mn and P fertilizers did not improve significantly the corn grain yield”
Claim · model-written summary
On a silty clay loam field, five factors accounted for 75% of the total soil variation.
- Taxon
- cornZea mays subsp. mayse2
- Outcome
- soil variatione0
- Value
- 75%e0
- Setting
- silty clay loame0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On the farm field with a finer textured silty clay loam soil, soil variation was decomposed into five factors, which accounted for 75% of the total variance”
e2“the application of Mn and P fertilizers did not improve significantly the corn grain yield”
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